Generalization of the Luttinger Theorem for Fermionic Ladder Systems

We apply a generalized version of the Lieb-Schultz-Mattis Theorem to fermionic ladder systems to show the existence of a low-lying excited state (except for some special fillings). This can be regarded as a non-perturbative proof for the conservation under interaction of the sum of the Fermi wave vectors of the individual channels, corresponding to a generalized version of the Luttinger Theorem to fermionic ladder systems. We conclude by noticing that the Lieb-Schultz-Mattis Theorem is not applicable in this form to show the existence of low-lying excitations in the limit that the number of legs goes to infinity, e.g. in the limit of a 2D plane.Comment: RevTex, 4 pages with 4 eps figure

Characterization of chitin and chitosan derived from Hermetia illucens, a further step in a circular economy process

Due to their properties and applications, the growing demand for chitin and chitosan has stimulated the market to find more sustainable alternatives to the current commercial source (crustaceans). Bioconverter insects, such as Hermetia illucens, are the appropriate candidates, as chitin is a side stream of insect farms for feed applications. This is the first report on production and characterization of chitin and chitosan from different biomasses derived from H. illucens, valorizing the overproduced larvae in feed applications, the pupal exuviae and the dead adults. Pupal exuviae are the best biomass, both for chitin and chitosan yields and for their abundance and easy supply from insect farms. Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscope analysis revealed the similarity of insect-derived polymers to commercial ones in terms of purity and structural morphology, and therefore their suitability for industrial and biomedical applications. Its fibrillary nature makes H. illucens chitin suitable for producing fibrous manufacts after conversion to chitin nanofibrils, particularly adults-derived chitin, because of its high crystallinity. A great versatility emerged from the evaluation of the physicochemical properties of chitosan obtained from H. illucens, which presented a lower viscosity-average molecular weight and a high deacetylation degree, fostering its putative antimicrobial properties

Time spent with HIV-RNA ≤ 200 copies/ml in a cohort of people with HIV during the U=U era

Objective: Zero risk of linked HIV transmission in sero-discordant couples when the HIV-infected partner had viral load (VL) <200 copies/mL (‘U status’) was found in observational studies. We aimed at estimating the proportion of time in which ‘U status’ was maintained and identifying factors associated with the risk of losing it. / Design: Observational cohort study. / Methods: We included participants in the ICONA cohort who had reached an established ‘U status’ (VL≤200 copies/mL for >6 months) as of December 2010. The outcome was the number of person-days of follow up (PDFU) above a VL>200 copies/ml, relative to the total number of PDFU observed. A logistic regression model was used to identify factors independently associated with the risk of losing ‘U status’. / Results: 8,241 persons living with HIV were included in the analysis who contributed 12,670,888 PDFU. Of these, 1,648 (20%) were female, 768 (9%) were people who inject drugs (PWID), and 2,066 (25%) were foreing-born. The median of VL measurements was 9 (IQR: 4–15). Overall, only 3.1% of PDFU were observed when VL was >200 copies/mL. The proportion of PDFU with VL>200 cp/ml was higher than average in females (5.3%), unemployed (5.4%), PWID (4.7%), and in people with>3 previous virologic failures (6.3%). These variables were significant predictors of losing ‘U status’ in the multivariable logistic regression. / Conclusions: Our results reinforce the validity of the U=U message in real-world setting. However, we identified subsets of our study population at higher risk of losing the ‘U status’ for whom additional efforts are needed

Is HCV elimination among persons living with HIV feasible? Data from the NoCo study in the setting of the ICONA cohort

Background and Aims: Whether the HCV test-and-treat strategy impacted on the rate of new HCV infections among PLWH in Italy is unknown. Methods: Prospective study of PLWH in the ICONA network. At baseline, PLWH were tested for HCV-Ab; HCV-RNA (if HCV-Ab positive) and, if positive, treated with DAA. SVR12 indicated eradication. Seroconversions and re-infections were evaluated yearly in HCV-Ab neg and HCV-RNA neg at first screening. We estimated the following: HCV seroconversions, incidence of HCV reinfections, and access to DAA and SVR12 rates tighter with factors associated with each outcome. Data were analysed by Cox regression, Poisson regression and logistic regression models. Results: Sixteen thousand seven hundred and forty-three PLWH were included; 27.3% HCV-Ab positive; of these, 39.3% HCV-RNA positive. HCV seroconversion incidence:.48/100 PYFU (95% CI:.36–.65); re-infections incidence: 1.40/100 PYFU (95% CI:.91–2.04). The risk factor for HCV re-infection was young age: aIRR 1.85, 95% CI: 1.17–2.95) per 10 years younger. 86.4% of HCV viremic in follow-up started DAA. PWID vs. heterosexuals (aHR.75, 95% CI.62–.90), HIV-RNA >50 copies/mL (aHR.70, 95% CI.56–.87), HCV genotype other than G1, G2, G3, G4 or with multiple/missing HCV genotype and post-COVID-19 calendar periods were associated with lower DAA access. 922/965 (95.5%) PLWH achieved SVR12. We estimated 72% reduction of chance to achieve SVR12 in PLWH with a CD4 count <200/mm3 (vs. CD4 ≥200/mm3 aOR.18, 95% CI:.07–.46). 95.5% of DAA-treated individuals eradicated HCV, but they represent only 53.2% of HCV viremic PLWH and 66.4% of those in follow-up. HCV-RNA positivity by year decreased from 41.7% in 2017 to 11.7% in 2022. Conclusions: The screening-and-treat campaign implemented in Italy, even if only partially effective, resulted in a dramatic drop in HCV circulation in our cohort

Phases of the two-band model of spinless fermions in one dimension

We study the two-band model of spinless fermions in one dimension for weak repulsive interactions. In this case, the model is equivalent to the weakly interacting spinless two-leg ladder. We obtain analytic expressions for the superconducting pairing correlation function and the charge density correlation function, which show, that a finite interchain hopping t_p results in dominant superconductivity for repulsive interactions (for vanishing t_p, we recover previous results). We furthermore find that the transition from the superconducting phase to the usual one-dimensional (Luttinger) metal at large doping occurs via a mixed phase, where superconducting pairs are formed in the bonding band only. We give the phase diagram as a function of temperature and doping.Comment: 10 pages, 2 figure

Classification and Stability of Phases of the Multicomponent One-Dimensional Electron Gas

The classification of the ground-state phases of complex one-dimensional electronic systems is considered in the context of a fixed-point strategy. Examples are multichain Hubbard models, the Kondo-Heisenberg model, and the one-dimensional electron gas in an active environment. It is shown that, in order to characterize the low-energy physics, it is necessary to analyze the perturbative stability of the possible fixed points, to identify all discrete broken symmetries, and to specify the quantum numbers and elementary wave vectors of the gapless excitations. Many previously-proposed exotic phases of multichain Hubbard models are shown to be unstable because of the ``spin-gap proximity effect.'' A useful tool in this analysis is a new generalization of Luttinger's theorem, which shows that there is a gapless even-charge mode in any incommensurate N-component system.Comment: 15 pages revtex. Final version as publishe